The present application relates generally to a method and system for diagnosing a squib loop for the fault condition of a short circuit between critical connections in a common connected pair of squib loops.
An airbag system typically includes a restraint control module, a reaction canister, an air bag, and an inflator with ignitor (squib) that are stored inside the reaction canister. The inflator with squib is connected to the restraint control module via conductive wires and connectors. The total electrical path of these wires and connectors to and from the inflator is termed “squib loop”. The restraint control module provides sufficient energy to the inflator through the squib loop to provide airbag actuation. The inflator is actuated by the restraint control module once appropriate signals are received from vehicle sensors sufficient to warrant airbag activation. The restraint control module controls the overall operation of the air bag system and can be viewed as the main control unit for the air bag system.
As with any electrical system that consists of sensors, airbag, wiring and connectors etc, the system requires electrical connections to operate properly. Specifically, in airbag safety systems customers demand that diagnostic capability be implemented in the restraint control module to interrogate the squib loop characteristics, that may prevent the air bag from being activated properly. An example of one squib loop characteristic is the squib resistance measurement between the feed line of one squib loop (SFx) and the second feed line of the second squib loop (SFy) of a common connected pair of squib loops.